Thursday’s episode was the show’s most-watched ever with 17.4 million viewers.

Big Bang also delivered a season high in the demo with a 5.5 rating among adults 18-49. This is all particularly impressive since most other shows are starting to soften in the ratings this week as we edge toward the holidays. Here’s EW.com’s rundown of last night’s episode, which was dubbed a throwback to earlier seasons.

What’s particularly amazing about Big Bang Theory is it airs at 8 p.m. It’s winning TV’s most competitive night by a large margin – with no lead in. Just jump-starting cold to 17+ million viewers.

The comedy’s huge rating gave CBS a tsunami effect down the night. Two and Half Men (13.9 million, 4.1) hit a season high. Person of Interest (14.5 million, 3.1) hit a season high to tie ABC’s Grey’s Anatomy in the demo (8.7 million, 3.1). And Elementary (10.7 million, 2.3), well, not a season high, but still up a tenth.

Up against Big Bang, ABC’s Last Resort (5.8 million, 1.3) went down a tenth. Frustrating, this was a strong episode last night and the show is awaiting word on whether it’s going to get a full season.

Also last night: Fox’s X-Factor was up 4 percent not facing a special Voice this week. Glee was down 13 percent. ABC’s Scandal was up 11 percent. NBC’s comedy block was super soft, with anchor The Office down 17 percent from last week to tie its series low. The CW’s Vampire Diaries was down 20 percent and Beauty and the Beast slipped a tenth.